Research and Technology Status on Hydrogen and AmmoniaFiring of Gas Turbine Burners in Norway

Andrea Gruber, James DawsonJapan-Norway Hydrogen Seminar 2020

Tokyo, February 25th 2020

The context: zero-emission thermal power cycles

Carbon-free firing of gas turbines: technology readiness & potential impact

Research challenges: stabilize flame, minimize fuel-dilution and emissions

Outline

Contributors:

Sponsors:

Acknowledgments

Nicholas WorthAssoc Professor

Jose AguilarNTNU Postdoc

Eirik. ÆsøyNTNU PhD st.

Mirko BothienAnsaldo Energia

Jenny LarfeldtSiemens Energy

2020-2050 timelinePolicy & energy trends

in EU:

“Hydrogen is set to be a key energy carrier in the future and indispensable in order for the German and other economies to become climate neutral…” , “… this includes both renewable-power-based green hydrogen and blue hydrogen from natural gas with CCS.” Peter Altmaier, BMWI (Dialogprozess Gas 2030, October 2019)

Thermalgenerators required to

stabilize grid!!!

Present European context...

Air-breathing thermal power cycles:powering the world

Gas + steam turbine (combined cycle): 50-800 MW Cycle efficiency ~ 63% 6100 TWh installed capacity (NG-fired) Carbon-free firing of GTs ‘within grasp’

High-bypass turbofan engine: 100-600 kN thrust Cycle efficiency ~ 30-36% +30000 CFM56 sold Enough biofuel?

Thermal cycles are not intrinsically dirty but as clean as their fuel and combustion technology!

2-stroke, low-rpm ICEs: 10-80 MW Cycle efficiency ~ 55% HFO, Diesel and NG MAN ‘upgrading’ to NH3

Courtesy of MAN

Why hydrogen (and ammonia)?

Hydrogen (H2)

H2 to power completes the pre-combustion CCS value chain

Provides an optimal energy-carrier in large-scale energy storage schemes for integration of non-dispatchable & intermittent RES (power-to-gas-to-power)

Effectively a bridge between “fossil” and “green” energy sources (blue and green H2)

Ammonia (NH3)

Convenient H2-carrier for remote transport and/or long-term storage in all of the above

Represent a useful H2-diluent (for stable combustion in gas turbines)

Both are carbon-free fuels: zero CO2 emissions!

Gas turbines (Brayton cycle): an example

Ansaldo’s GT36

Why gas turbines?

SGT-750 / Courtesy of Siemens

High cycleefficiency up to ~63% CCGT /

~90% CHP

Unmatchedspecific power~2-10 kW/kg

Fast response to load variations up to ~50 MWe/min

High avaliability(~1 stop/year)

and long lifetime(+25 years)

High fuel flexibilityachievable from liquid HC/NG to

H2/NH3

Switch to H2/NH3only requires

burnermodifications

GTs handle wellimpurities &

«minor» species in fuel (e.g. CO2)

Relatively «lowcost» at 200-

1200 USD/kWe(SCGT-CCGT)

H2-fired GTs: brief history and state of the artFP6 ENCAPCO2

(2004-2009): preliminary

investigations

FP7 DECARBit and BIGH2/Phase I&II

(2008-2015): 50% by vol H2 in NG is achieved in rig

AE provides 50% H2 in H-class GT36 (2018)

SIT provides 50-60% H2in GT600/700/800 (2018)

The race is on (2019)!

AE achieves 70% H2 in rig @ H-classtemperature (baseload GTs)

SIT achieves 100% H2 in rig @ F-class temperature (industrial GTs)

GT OEMs commited to 100% H2 firing by 2030GT-industry’s expertise and resources committed to achieve 100% H2, however:

High-pressure/full-size R&D of GT combustion system is extremely expensive and cash-flow is limiting factor

Interest by committed customers is needed

Public intervention is beneficial in the form of

- A legal framework for non-conventional fuels

- Set goals, do not pre-select technologies

- Public co-funding of RD&D efforts

The challenge: the high reactivity of hydrogen

Key factors in design of gas turbine combustors include:

the combustion velocity (flame speed)

the fuel reactivity and flammability (time and composition needed for ignition)

the flame temperature (controlling dilatation and acceleration of the working fluid in GTs)

Stoichiometric combustion properties at 1 bar and 300 K CH4 H2 NH3

Flame Speed 40 cm/s 300 cm/s 20 cm/s

Flame Temperature ~2200 K ~2400 K ~2050K

Flammability Limits(by volume %)

5-15 4-75 15-28

Ignition Energy (mJ) 0.28 0.011 680

Ignition Delay Time (ms) @ 1000K/17bar 45.6 6.2 N/A

LHV (MJ/Kg) 50 120 18

Standard Too reactive! Too littlereactive!

How to address hydrogen’s high reactivityTwo strategies at hand for clean, stable and efficient hydrogen combustion in GTs:

“handle H2 reactivity” (e.g. combustion staging) relies on autoigniton for flame stabilization

“reduce H2 reactivity” (e.g. fuel blending) relies on inert gases or less reactive fuels

SINTEF & NTNU work together with gas turbines OEMs at both approaches:

Auto-ignition H2 flame stabilization in FME NCCS/Task 5 (+Reheat2H2 KPN) w/Ansaldo

Hydrogen/nitrogen/ammonia-firing of a Siemens DLE burner (BIGH2/Phase III)

H2 co-firing in DLE burners by Siemens

*Larfeldt et al. “Hydrogen co-firing in Siemens low NOx industrial gas turbines”, PowerGen 2018

*

BIGH2Phase III

Ansaldo’s sequential combustion technology

Courtesy of Ansaldo Energia

Combustion system consists of two burners (stages) arranged in sequence

Optimally suited for fuel and load flexibility

Other vendors are pursuing similar approaches (e.g. GE’s AFS)

Reheat scheme for H2 combustion does not adopt conventional “solutions”: De-rating of the engine Heavy steam or nitrogen dilution (typically ~10 KgN2/KgH2 to comply with emission limits)

Why staged H2-combustion? Ansaldo’s reheat scheme: firing temperature of 1st stage

controls ignition time (tign) and flame stabilization in 2nd stage!

Courtesy of Ansaldo Energia

Bottom line: large-scale power generation with hydrogen-rich fuels is feasible and R&D can help filling the remaining gap!

*Bothien et al, “Sequential Combustion in Gas Turbines – The Key Technology for Burning High Hydrogen Contents with Low Emissions”, Asme Turbo Expo 2019, GT2019-90798

*

Technical challengesCurrent GTs are highly “tuned” to burn NG-air mixtures and transitioning to carbon-free fuels needs to maintain:

low NOx capabilities

combustor stability and operating range

dynamic loading (turn down/part load)

… all of the above while avoiding de-rating of the engine

Knowledge gaps studied @ SINTEF/NTNU

Scientific (independent of combustor geometry)

The effect of pressure, temperature and fuel-oxidant mixture composition on:- Flame speed, ignition delay times, chemical kinetics, emissions, turbulence-chemistry interaction

Technical (some geometry dependence)

Ensure flame stabilisation to prevent:1) Static instabilities: flashback and blow-off2) Dynamic instabilities: thermoacoustic oscillations

Research approach @ SINTEF/NTNU To understand flame stabilization, static and dynamic instabilities we use simplified geometries

enabling detailed measurements and computations…

Research activities over a range of TRLs is essential High-pressure, single-sector combustion rig

Single sector and annular combustors(atmospheric pressure)

Increasing TRL

DNS of turbulent flames in simplified geometries

DNS example: stabilization of 100% H2 reheat flame

Flame propagation

Auto-ignition

% of total H2 fuel consumption rate quantified from Chemical Explosive Modes Analysis

*Konduri et al, “Direct numerical simulation of flame stabilization assisted by autoignition in a reheat gas turbine combustor”, Proc Combust Inst 2019, vol. 37, pp. 2635-2642

H2 co-firing: ammonia/hydrogen/nitrogen vs methane

Devise and investigate optimal NH3/H2/N2 mixture (fundamentals and simple lab flames)- Initial choice for mixture is 40% NH3 / 45% H2 / 15% N2 (approx matches NG

laminar flame speed Sl and temperature Tad)

Obtain guidelines to achieve flame stabilization and NOx emissions control

High-pressure testing in scaled version of SGT-750 burner and demonstrate in GT

Aim to “mimic” natural gas with ammonia blend for potential retro-fit of installed fleet

Ammonia/hydrogen/nitrogen vs methane: Tad

0.2 0.4 0.6 0.8 1 1.2 1.4 1.61000

1200

1400

1600

1800

2000

2200

2400

Methane

Ammonia blend

Non pre-heated (300K) Pre-heated (750K)

Unstrained laminar flame thickness is also very similar between methane and the ammonia blend…

DNS of Ammonia/hydrogen/nitrogen vs methane: aext

Methane @ Tu=750K and φ=0.45 blows off between 11-12 m/s

40% ammonia / 45% hydrogen / 15% nitrogen mixture @ Tu=750K and φ=0.45 blows off above 60 m/s!

Ammonia/hydrogen/nitrogen vs methane: aext

Counterflow inlet velocity vs distance between flame fronts, non-normalized (left) and normalized (right)

«An Updated Short Chemical-Kinetic Nitrogen Mechanism for Carbon-Free Combustion Applications» Y.Jiang, A.Gruber, K.Seshadri, F.A.Williams - Int J Energy Res, vol. 44(2), pp. 795-810.

Ammonia/hydrogen/nitrogen vs methane: blow-off exp.

40%NH3/45%H2/15%N2 blend has similar Tad and SL as methane but exhibitsorder-of-magnitude deviation in blow-off limits

*Wiseman et al, “A comparison of the blow-out behaviour of turbulent premixed ammonia/hydrogen/nitrogen-air and methane-air flames”, submitted to Proc Combust Inst

Ammonia/hydrogen/nitrogen vs methane: turb-chem int.

3-D DNS of premixed temporal jet flames (parametric study w/S3D Legion code, 50 MHrs)

Ammonia/hydrogen/nitrogen blend Methane

*Wiseman et al, “A comparison of the blow-out behaviour of turbulent premixed ammonia/hydrogen/nitrogen-air and methane-air flames”, submitted to Proc Combust Inst

Dynamic instabilities: understanding thermoacoustics?

Thermoacoustic feedback loop Stable – to violent – to very violent

Heat release fluctuations

q’

Acoustic oscillations

p’

Flow fluctuations,

u’

Addition of a small amount of H2

Co-firing: effect of increasing H2 fraction on flame shape

Mean H2/CH4 - air flame shapes for increasing H2

Conditions: Power = 7kWPower fraction, PH2: 0-28%

Volume fraction: 0-50%

Equivalence ratio = 0.7

PH2 :0% PH2 :5% PH2 :10% PH2 :15% PH2 :20%

PH2 :23% PH2 :23% PH2 :25% PH2 :27% PH2 :28%

Hysteresis Self excited

Co-firing: effect of increasing H2 fraction on FTF

H2 flames respond differently from CH4 to acoustic disturbances

Combustion dynamics in annular combustors

Spinning and standingmodes

Ongoing high-pressure burner testing in HIPROX rig (thermal power ~ 100 kW) complement full-scale tests

Ansaldo’s Flamesheet burner Siemens’ DLE burner

Concluding remarks

Combustion of carbon-free fuels is a technically viable route to large-scale decarbonisation for the power generation sector

Significant steps forward in hydrogen co-firing with natural have been already been made and GTs are commercially available (~50% H2 by vol)

There are still significant (and exciting!) scientific and technical challenges in combustion technology to get to zero carbon that need to be addressed

Collaborative research initiatives with interested stakeholders in Japan are welcome!